1. Technical Field
The present invention relates generally to semiconductor devices and the fabrication thereof, and more particularly, to the design of a semiconductor device using an etch resistant liner on a transistor gate and/or a resistor gate.
2. Related Art
Spacers are conventionally used to protect the sidewalls of a gate stack during the processes required to form silicide on a top surface of the gate stack and within the source/drain region of a transistor. Prior to the formation of silicide the wafer undergoes a conventional preclean process to prepare the top surface of the gate stack and the source/drain region for silicide formation. Unfortunately, the spacers are not resistant enough to withstand the proclean process, and portions of the spacer may become inadvertently removed. As a result, portions of the gate stack sidewall become exposed. The exposed portions of the gate stack sidewall are then susceptible to silicide formation. Silicide formed on the sidewalls of the gate stack can lead to electrical shorts between the silicide on the top of the gate stack and the silicide within the source/drain region at the base of the gate stack. As semiconductor devices are continually being scaled down, and the distance between the top of the gate stack and the source/drain region is being reduced, the likelihood of electrical shorts due to the silicide formed on the sidewalls of the gate stack increases.
The preclean process mentioned above also tends to affect resistors formed adjacent to the transistors. In order to maintain the designed resistance it is desirable to prevent silicide formation within or around the resistor gate stack. Portions of the spacers protecting the sidewalls of the resistor gate stack may become removed during the preclean process. As with the transistor, the exposed portions of the resistor gate stack are susceptible to silicide formation, which tends to decrease resistance.
Therefore, there is a need in the industry for a method of forming a transistor and/or resistor gate that overcomes the above problems.